U.S. Pat. Nos. 3,294,131; 3,461,928; 3,536,113; 4,269,241; 5,377,730; 6,123,124; and 6,408,906, the teachings of which are incorporated herein by reference, illustrate tree harvesting, cutting and gripping apparatus mounted on an adjustable boom and used for gripping the tree above a line of cut, cutting the tree along the line of cut and then dropping or moving the cut top or other cut portion to the ground.
Problems arise when the tree being harvested is in a suburban area and is close to a fence, house, shelter or the like, any of which might be struck and damaged when the cut tree top or other cut portion of the tree is believed to be unusually heavy and is released and allowed to free fall to the ground and risk damaging structures in its path. Therefore, in some instances, the cut portion is lowered to the ground while still remaining gripped. Heretofore, there has been no way for measuring the actual weight of a cut tree top, a tree length, or block prior to its being dropped or lowered to the ground. Excessive handling time thus becomes involved when the boom mounted cutting and gripping apparatus is used to lower a cut top, limb, short block, or other cut portion of a tree to the ground, even though the cut top, limb or block might otherwise be within a prescribed safe weight limit. Risks are also taken when the actual weight of a cut top or other cut portion of a tree is so heavy as to overload the boom and cause it to tip over.
One known first practice for harvesting a tree is to cut the tree at its base and allow it to fall. An alternative second practice for harvesting a tree involves an operator being lifted by a so called “Bucket Truck” to a position near the top of a tree and harvesting the tree by trimming limbs and cutting short blocks which are lowered or allowed to free fall to the ground. A rope tied to a tree top, a limb or a short block and pulled by hand or tractor is sometimes used in this alternative second practice to avoid damage to a house, a shed, a power line or other structure in the path of the tree top, limb or short block being lowered. Use of a crane and a climber with a chain saw has been a third harvesting practice for harvesting trees by trimming limbs and cutting short blocks.
Prior to the present invention, the tree service industry has thus had to rely primarily on time consuming and sometimes hazardous tree harvesting apparatus and methods that depend upon the tree being either cut at its base and allowed to fall with risk of damage to anything in its path or having the tree top, limbs and short blocks individually cut from the tree and either lowered or allowed to free fall to the ground. In none of the prior art practices however, has the operator been able to measure the actual weight of a tree top, limb or short block after it has been cut but before it has been dropped or lowered to the ground. Overloading of the tree harvesting apparatus may and can occur with prior art practices.
While it has been known to provide an apparatus for monitoring and measuring the weight of a fixed load on a boom or on a forklift, such as described in U.S. Pat. Nos. 3,990,584; 3,993,166; 4,456,093; and 4,746,024, the teachings of which are also incorporated herein by reference, it has not been known, so far as applicant is aware, to provide an apparatus and method associated with a tree harvesting, cutting and gripping apparatus which enables a cut top or other cut portion of a tree after such portion has been cut to be supported by the outer end of a boom and be weighed before being lowered or allowed to free fall to the ground.
Construction forklift apparatus made by Manitou North America, Inc. of Waco, Tex. (hereafter sometimes referred to as “Manitou”) is well known in the trade and provides in its Model MRT 2150, referred to by way of example, a computerized system for measuring and displaying the weight of a load of construction material placed on a forklift mounted at the end of a boom. The turntable on which the boom of the Manitou apparatus is mounted rotates 360°. In the Manitou Model MRT 2150 being used for reference, the forklift itself can be lowered to essentially ground level or be raised to a height of almost 70 feet to reach and pick up or deliver a load of construction material for a multi-story building, for example. The Manitou forklift construction apparatus also has means for measuring and displaying the height at which the forklift is located and inputing this height as a signal to its computer. The Manitou apparatus also has means for measuring and displaying the horizontal distance between the center of the boom turntable and the projected location of the forklift on the horizontal plane passing through the base of the boom. A signal representing this distance is also inputted to the Manitou apparatus computer as one factor in helping determine the likelihood of the Manitou apparatus tipping when the boom is at a particular height and angle and is carrying a particular load. Thus, by appropriate programming and calibration, the Manitou apparatus is able to signal its operator at ground level through what Manitou refers to as a “Load Movement Indicator” whenever the Manitou forklift is being overloaded at the particular height and angle at which the boom is disposed.
So far as is known, no one prior to the present applicant has recognized the significance of incorporating weight measuring, height measuring and distance measuring such as found in the Manitou type forklift to the field of tree harvesting and particularly to the task of harvesting trees in crowded suburban areas. More specifically, no one prior to this applicant has recognized that tree cutting and clamping apparatus can, in place of a forklift, be mounted on a boom such as found in the Manitou apparatus and be equipped and operated in such a way as to enable the weight of a tree top or other cut portion to be measured after it has been cut and after its weight has been placed on and transferred to the end of the boom on which the tree cutting and clamping apparatus is mounted in order to be able to determine how such cut portion can best be safely transferred from its elevated position to the ground.
Thus, the principal object of the invention is to provide a tree harvesting method and apparatus for general application to tree harvesting but particularly adapted for use in a crowded suburban area and, which enables a treetop or other cut portion of a tree being harvested to be gripped and weighed prior to being lowered or allowed to free fall to the ground. Another object is to provide a tree harvesting method and apparatus of the type described which is suitable for use in both a crowded suburban area as well as in a totally forested area for harvesting all of the trees accessible within a 360° swing of a boom on which the apparatus is mounted. Other objects will become apparent as the description proceeds.